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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 3 |
| 4 | 13 |
| 5 | 71 |
| 6 | 465 |
| 7 | 3539 |
| 8 | 30637 |
| 9 | 296967 |
| 10 | 3184129 |
| 11 | 37401155 |
| 12 | 477471021 |
| 13 | 6581134823 |
| 14 | 97388068753 |
| 15 | 1539794649171 |
| 16 | 25902759280525 |
| 17 | 461904032857319 |
| 18 | 8702813980639617 |
| 19 | 172743930157869827 |
| 20 | 3602826440828270029 |
| 21 | 78768746000235327495 |
| 22 | 1801366114380914335441 |
[0,1,3,13,71,465,3539,30637,296967,3184129, 37401155,477471021,6581134823,97388068753, 1539794649171,25902759280525,461904032857319, 8702813980639617,172743930157869827, 3602826440828270029,78768746000235327495, 1801366114380914335441] |